You should find some example sentences using fall apart and crumble, and then consider if they hold the meaning you intend. If still some question, add them to your question.
– user3169Jun 22 '18 at 2:13

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It's unclear to me what you mean by "air waves". Do you mean wind? It's not necessarily very windy during a thunderstorm. Or if you mean sound, you could say "sound waves". But I don't think sound waves would affect the ground very much at all.
– ellJun 26 '18 at 19:01

7 Answers
7

First, I like the image of the ground falling apart or crumbling. LawrenceC is correct, that this is not a common usage, but you seem to be writing something more poetic and less literal, and it certainly paints a vivid image.

The edge of a cliff (also known as a "bluff") may be described as falling apart or crumbling. So, if you are trying to give a sense that the thunderstorm made the subject feel as if the very earth were about to give way - that's a fantastic way of putting it!

Now, I wouldn't recommend using the "fall apart/crumble" in the work. A slash is awkward and probably incorrect. "Crumble" includes the meaning of falling apart, so it is fine on its own. Now on to the rest...

The torrential downpour has loud-banging sound because of thunder that is so intense the air waves from it...

Here, I agree with others that there are both word-choice problems (specifically, "air waves") and an overly complex and redundant sentence structure. I would recommend a simpler, more direct sentence, such as

The torrential downpour slammed the earth. The deafening roar of the thunder seemed to shake the ground, as if it were going to crumble.

I like this, this is probably the best. However I'd like to change ''the deafening roar'' to ''deafening sound'' to make not so figurative, so to speak.
– John ArvinJul 3 '18 at 8:38

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"Deafening sound" is certainly proper English, and would be fine. But in terms of style, specific is usually better than generic. Sound is generic - it can be a pin dropping or a bomb exploding. If you don't want to say "roar", maybe you can find a different sound-descriptor that better describes what you are saying. ex. "the deafening explosion", "the deafening throb", "the ear-shattering roar", etc.
– ScyllaGregJul 3 '18 at 17:11

Fall apart means to break or decompose, and is used for things that are constructed or built. Ground and floor-like things can't "fall apart" - they can "break up", "break down", "break apart" but not "fall apart."

Crumble means to break into small pieces. Rain won't ever do that to ground unless flooding is involved, which is different than rain. Large sudden quantities of water can cause damage and crumbling to things like shores, lake edges, etc. but rain itself won't directly make anything crumble really.

Thunder doesn't cause wind or air waves. If you mean the sound, say sound waves.

Earth-shattering is a good word to use to describe a force that is so strong it could cause an earthquake or break large quantities of earth, and this can be used figuratively to express what you might be trying to say. Sound and wind can be earth-shattering.

The physical effect of a shock wave accompanying certain types of extremely loud sound (such as the sound of an explosion) might be termed its concussive force, where—to paraphrase Collins Dictionary—concussive means "producing violent shaking or jarring." The shock wave doesn't come from the sound, of course, but from the actual explosion (or in this case, lightning strike).

A good verb to describe the act of striking something (such as the ground) with enough force to break it apart is sunder, which Merriam-Webster defines as "to break apart or in two : separate by or as if by violence or by intervening time or space."

Here are a few meteorological terms that learners might find helpful to know.

Thunderstorms accompanied by torrential rain can make the ground rumble and crack. Lightning bolts produce shock waves so violent and powerful it seems that the ground could burst/split open.

torrential
When there's a torrential storm, there's so much rain falling so fast that you'll be soaked in about three seconds.
1.1 pouring in abundance: “torrential rains”

bolt
It's a quick, sharp word that either means to move quickly or refers to a stroke of lightning, as in "lightning bolt."
2. a discharge of lightning accompanied by thunder

burst
It usually means, "to explode outward, with noise" like if you burst into song in the middle of study hall, startling everyone. It also means, “to split open in a violent way due to internal pressure” like an overfilled water balloon. It comes from the Old English word berstan, meaning "break suddenly."

I think your answer is fine, but are fall apart and crumble, when combined, it becomes earth-shattering aren't they? You know I'm just making it to not become too wordy.
– John ArvinJun 29 '18 at 19:13

I'm sry, this is unreliable. Thunder or lightning is caused by positive-negative electrical discharges reaction with each other, clearly not from cloud but obviously takes places in cloud, you should have done your research about this. The rest are also I'm dubious about, thx anyway.
– John ArvinJul 2 '18 at 11:21

This is not a physics question, electron charge differentials require a medium. The presence of the cloud allowed the charge to build up. The specifics is that moisture in the cloud freezes and those small ice particles rub together causing the charge. No cloud No charge. I rest my case.
– Rob Jul 2 '18 at 14:06